The present invention relates generally to mechanical connectors and more particularly to mechanical connectors that secure two members together such that the connection is tamper resistant. More specifically, the present invention relates to tamper resistant fluid and electric connectors for use in plasma arc torches.
A manually operated plasma arc cutting torch typically comprises a power supply that supplies fluid (e.g., gas, liquid) flow and electric current to a torch head through a torch lead. The torch lead is often removably connected to the power supply such that a variety of power supplies may be used with a single torch head and torch lead combination, and vice versa. At the connection between the power supply and the torch lead, at least one negative lead or pin, which may also carry fluid, or cutting gas, is connected to the torch lead side of the connection. Typically, the pin is disposed within a housing to insulate and seal the fluid flow and electric current traveling through the pin. Additionally, a main power socket is connected to the power supply side of the connection, which is similarly disposed within a housing, along with additional electrical connections for operation of the torch. Accordingly, the negative lead is inserted within the main power socket when connecting the torch lead to the power supply.
In power supplies of the known art, the negative lead is often designed to be field-replaceable such that as the negative lead wears during service due to both high voltages during operation and frictional wear when connecting and disconnecting the torch lead, the negative lead can be easily replaced in the field. Unfortunately, the replaceability of the negative lead often results in users installing an improper negative lead such that unsuitable equipment, e.g. torches, are mistakenly connected to the power supply. As a result, the torch may function improperly or parts may wear prematurely.
In power supplies that do not have a field-replaceable negative lead, the negative lead can be installed in a variety of ways. For example, the negative lead may be co-processed with the housing in an injection molding process, threaded into the housing, or the negative lead may be bonded or otherwise secured within a two-piece housing body, which allows access for assembly and/or disassembly. However, the installation of a negative lead that is not field-replaceable into housings of known art plasma arc power supplies is relatively time consuming and adds further cost to the torch and torch lead.
Accordingly, there remains a need in the art for a connector that provides a tamper resistant connection between a negative lead of a torch lead and a main power socket of a power supply in a plasma arc cutting apparatus. A further need exists for a tamper resistant connector that is capable of connecting both fluid, (e.g., gas, liquid), as well as electric conductors, yet which is relatively simple to install and relatively low cost.
In one preferred form, the present invention provides a connector for use in a plasma arc cutting apparatus comprising a housing defining a hollow internal channel, wherein at least one locking finger is disposed that engages a pin to secure the pin within the housing. Accordingly, the pin defines a first collar with a shoulder disposed thereon such that the locking finger engages the shoulder to secure the pin within the housing. Additionally, the hollow internal channel further comprises a first portion and the pin further defines a second collar such that the second collar blocks access to the locking finger through the first portion of the hollow internal channel. As a result, the locking finger cannot be accessed to disengage the pin as the second collar engages the first portion of the hollow internal channel. Furthermore, the pin is recessed within a second portion of the hollow internal channel when the locking finger fully engages the shoulder, thereby restricting access to the pin such that the connection remains tamper resistant.
Preferably, the pin is a negative lead gas carrying pin, and the housing is a plug housing that is secured to a torch lead side of a quick disconnect connector between the power supply and a torch lead in a plasma arc cutting apparatus. Accordingly, the negative lead gas carrying pin is secured within the connector of the torch lead side such that the connection is tamper resistant, thus preventing users from replacing damaged or worn pins with improper pins into the connector of the plasma arc cutting apparatus.
In another preferred form, the present invention provides a housing for use in connecting a pin in a plasma arc cutting apparatus that similarly comprises a hollow internal channel and at least one locking finger disposed within the hollow internal channel that engages the pin, which is inserted into the hollow internal channel, to secure the pin within the housing such that the connection is tamper resistant. Preferably, the locking finger is integrally formed within the hollow internal channel, as a part of the housing, and the pin slidably engages a first portion of the hollow internal channel such that the locking finger cannot be accessed to disengage the pin. Additionally, the pin is recessed within a second portion of the hollow internal channel to further restrict access to the pin and thus providing a tamper resistant pin connection.
In yet another preferred form of the present invention, a pin for use in a plasma arc cutting apparatus is provided that comprises a first collar and a shoulder disposed thereon, wherein the shoulder is engaged by a connecting member to secure the pin within the connecting member such that the connection is tamper resistant. Additionally, the pin may further comprise a second collar that blocks access to the shoulder such that the pin may not be disengaged from the connecting member.
As used herein, a plasma arc apparatus shall be construed by those skilled in the art to be an apparatus, whether manual or automated, that generates or uses plasma for cutting, welding, spraying, or marking operations, among others. Accordingly, the specific reference to plasma arc cutting torches or plasma arc torches herein shall not be construed as limiting the scope of the present invention.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.